Witnesses who survived the carnage told investigators Tashfeen Malik, 29, and her husband, Syed Farook, 28, prepared to open fire from opposite sides of a door to the conference room in the Inland Regional Center, The Sunday Times of London reported.

Malik assumed a firing stance and blasted a group of workers near a Christmas tree as Farook hesitated for a moment — perhaps temporarily losing his nerve or looking for a specific person, according to the report.

The new details of the massacre that left 14 dead and 21 injured came as a clearer portrait emerged of Malik.

"She used to talk to somebody in Arabic at night on the Internet," said the relative, speaking anonymously from Malik's hometown of Karor Lal Esan, Pakistan.

"None of our family members in Pakistan know Arabic, so we do not know what she used to discuss."

Neighbors and classmates remembered her as quiet, studious and unimposing, her face usually veiled. "She was religious, but a very normal person as well," a professor, Nisar Hussain, told the Los Angeles Times.

"She was a very hardworking and submissive student."

Police said Malik gave a social media shoutout to ISIS leader Abu Bakr al-Baghdadi around the time she and her husband carried out their attack. They were killed hours later in a shootout with authorities.